1. Field of the Invention
The present invention relates to a display apparatus and a method for driving the same, and more specifically, to a display apparatus capable of improving a display quality and a method for driving the display apparatus.
2. Discussion of the Background
In general, a liquid crystal display (LCD) includes a liquid crystal display panel (LCD panel) for displaying an image. The LCD panel has a lower substrate, an upper substrate facing the lower substrate, and a liquid crystal layer interposed between the lower substrate and the upper substrate. The lower substrate of the LCD panel includes gate lines, data lines and pixels. Each pixel is electrically connected to a corresponding gate line and a corresponding data line.
The LCD may have a narrower viewing angle than other display apparatuses. In order to improve the narrower viewing angle of the LCD, various driving modes have been suggested, including the patterned vertical alignment (PVA) mode, the multi-domain vertical alignment (MVA) mode, and the super patterned vertical alignment (SPVA) mode.
Each pixel in an LCD driven in SPVA mode includes a main pixel and a sub pixel. In order to form domains having different gray scales from each other in each pixel, the main pixel and the sub pixel include a main pixel electrode and a sub pixel electrode, respectively. Further, a main pixel voltage and a sub pixel voltage, having different voltage levels from each other, are applied to the main pixel electrode and the sub pixel electrode, respectively. As human eyes recognize an intermediate value between the main pixel voltage and the sub pixel voltage, degradation of a side viewing angle caused by distortion of a gamma curve under an intermediate gray-scale value is prevented. Therefore, side visibility of the LCD is improved and the narrower viewing angle is widened.
The SPVA mode LCD may be classified as a coupling capacitor (CC) type or a two-transistor (TT) type according to a driving method thereof. In the CC-type, a coupling capacitor is coupled between the main pixel electrode and the sub pixel electrode to level down a data voltage applied to the sub pixel electrode. The sub pixel voltage, which has a lower voltage level than that of the main pixel voltage, is charged in the sub pixel by the coupling capacitor. In the TT-type, a first transistor is connected to the main pixel electrode to supply the main pixel voltage, and a second transistor is connected to the sub pixel electrode to supply the sub pixel voltage. Also, the main pixel voltage has a voltage level different than the voltage level of the sub pixel voltage.
Recently, in order to improve brightness reduction and an afterimage phenomenon that may occur in the CC-type SPVA mode LCD, a charge sharing (CS) type has been suggested. However, in the CS-type SPVA mode LCD, the main pixel voltage and the sub pixel voltage respectively applied to the main pixel and the sub pixel are controlled during a next horizontal scanning period. However, the main pixel voltage and the sub pixel voltage applied to the main pixel and the sub pixel connected to a last gate line are not controlled since there is no next horizontal scanning period after the last gate line. As a result, a whitening phenomenon may occur where the pixels connected to the last gate line emit a brighter light than the light emitted by other pixels in the display apparatus.